Unitary crank spindle assembly and method of fabrication

ABSTRACT

A bicycle is provided having a unitary steering tube-crown member and a unitary crank arm-spindle member. A multistage aluminum 3D forging process is used to form the unitary members. This may allow the fabrication of components with substantially hollow interior areas to reduce weight, reduce part count while maintaining high strength and ductility. The multistage 3D forging process provided also allows the combination of multiple components into a single unitary part.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional application of U.S. PatentProvisional Application No. 61/160,397 entitled “UNITARY CROWN FORKASSEMBLY AND METHOD OF FABRICATION” filed Mar. 16, 2009, which is herebyincorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to a bicycle and inparticular to a bicycle having a unitary crank spindle component.

Bicycles, such as mountain bicycles and all-terrain bicycles encounter avariety of terrains and environmental conditions during operation.Therefore, components used in bicycles need to withstand impacts causedby bumps, rocks, holes and the like. This results in the componentsbeing made from strong materials to avoid damage. However, otherfactors, such as weight for example, may also determine materialselection since a lighter bicycle makes less of an impact on the ridersendurance.

To accommodate these factors, tradeoffs are made in the selection ofmaterial and design of components. It may be desirable to have acomponent that absorb energy, such as the front fork assembly forexample, be made from high strength steel. However, it may beundesirable to incur the additional weight of a steel component. Toachieve a high strength and low weight fork assembly, compositematerials, such as carbon composites for example, have been proposed.While forks made from these materials perform well, they tend to beexpensive to manufacture. Further, while composite materials are strong,they are also less elastic than traditional metal materials. As aresult, higher performing composite materials are used, which furtherincreases the cost.

Bicycles include a number of subassemblies, such as the front steerertube-fork or the crank-spindle assemblies for example. Each of thesesubassemblies is typically composed of a number of components. Forexample, the front fork assembly includes a steerer tube, a crown, andone or more suspension forks. While the fabricating individualcomponents may be desirable to allow flexibility in material selectionand design of the components, it does adversely impact the manufacturingcosts of the bicycle.

Accordingly, while existing bicycles are suitable for their intendedpurposes, there remains a need for improvements, particularly in themanufacturing of unitary components to reduce the number of componentswhile maintaining desired performance.

BRIEF DESCRIPTION OF THE INVENTION

According to one aspect of the invention, a bicycle is provided having awheel and a head tube. A unitary fork is operably coupled to the wheel.The fork includes a steerer tube operably coupled to the head tube, thesteerer tube includes a first bore having a first axis. The fork furtherincludes a crown contiguously extending from one end of the steerertube. Wherein the fork is made from a three-dimensional (3D) forgedmetal material.

According to another aspect of the invention, a method of fabricating aunitary bicycle fork is also provided. The method includes the step ofperforming a first forging on a billet to form a first projection. Afirst 3D forging operation is performed on the billet extending thefirst projection to form a crown. A second 3D forging operation isperformed on said billet to form a steering tube, wherein the secondprojection is substantially perpendicular to the first projection.

According to yet another aspect of the invention, a unitary bicycle forkis provided having a crown formed by a first 3D forging of a metalbillet to form a first projection. A steerer tube is extended from thecrown, the steerer tube formed by a second 3D forging, where the steerertube has a first axial bore therein.

According to yet another aspect of the invention, a crank assembly for abicycle is provided. The crank assembly includes a unitary firstportion. The first portion having a first arm with a first solid end andan first axial bore extending from the first end to a second end. Thefirst portion further having a spindle extending substantiallyperpendicular from the arm adjacent the second end. The spindle has asecond axial bore extending into the first arm adjacent the second end,the second axial bore being arranged to intersection with the firstaxial bore. A second portion is provided having a second arm with athird solid end and an third axial bore extending from the third end toa fourth end, the second portion being operably coupled to the spindleadjacent the fourth end.

According to yet another aspect of the invention, a method offabricating a unitary bicycle crank-arm and spindle is provided. Themethod includes forming a first elongated arm by 3D forging. The firstarm having a solid first end and a first axial bore, the axial borehaving a first opening at a second end of the first arm opposite thefirst end. A first projection is formed on the first arm adjacent thesecond end. Extending the first projection forms a spindle and a secondaxial bore in the first projection by 3D forging. The arm is then bentsuch that the solid end is substantially perpendicular to the firstprojection.

These and other advantages and features will become more apparent fromthe following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWING

The subject matter, which is regarded as the invention, is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features, and advantages ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIG. 1 is a side plan view illustration of a bicycle in accordance withan embodiment of the invention;

FIG. 2 is a partial side plan view illustration of the bicycle of FIG.1;

FIG. 3 is a perspective view illustration of unitary steerer tube-crownembodiment for the bicycle of FIG. 1;

FIGS. 4-6 are perspective sectional view illustrations of embodiments ofthe unitary steerer tube-crown of FIG. 3;

FIG. 7-10 are an illustration of a unitary steerer tube-crown-bladeembodiment for the bicycle of FIG. 1;

FIG. 11-16 are an illustration of another unitary steerer tube-crownembodiment for the bicycle of FIG. 1;

FIG. 17-22 are an illustration of another unitary steerer tube-crownembodiment for the bicycle of FIG. 1;

FIG. 23-28 are an illustration of another unitary steerertube-crown-blade embodiment for the bicycle of FIG. 1;

FIG. 29-30 are an illustration of another embodiments for a unitarysteerer tube-crown-blade or unitary steerer tube-crown for the bicycleof FIG. 1;

FIG. 31-38 are an illustration of a process for fabricating a unitarysteerer tube-crown-fork in accordance with an embodiment of theinvention;

FIG. 39-44 are an illustration of a process for fabricating anotherunitary steerer tube-crown-fork having a single fork in accordance withan embodiment of the invention;

FIG. 45 is a side plan view, partially in section, of the fabricatedsteerer tube-crown-fork of FIG. 44;

FIG. 46-48 are an illustration of assembling a blade insert in thesteerer tube-crown-fork of FIG. 45;

FIG. 49-50 are perspective view illustrations of the finished steerertube-crown-fork of FIG. 48;

FIG. 51 is a perspective view illustration of an alternate finishedsteerer tube-crown-fork;

FIG. 52 is an exploded perspective view illustration of a crank assemblyembodiment for the bicycle of FIG. 1;

FIG. 53-60 are an illustration of a process for fabricating a unitarycrank-arm and spindle member for the crank assembly of FIG. 52;

FIG. 61-66 are an illustration of the unitary crank-arm and spindlemember of FIG. 55 and FIG. 56;

FIG. 67-71 are an illustration of the unitary crank-arm and spindlemember of FIG. 57 and FIG. 58;

FIG. 72-76 are an illustration of the unitary crank-arm and spindlemember of FIG. 51;

FIG. 77-80 are an illustration of the unitary crank-arm and spindlemember of FIG. 60 with a plug being inserted;

FIG. 81-87 are an illustration of the unitary crank-arm and spindlemember of FIG. 60 with secondary operations completed;

FIG. 88-89 are an illustration of the unitary crank-arm and spindlemember of FIG. 52 with another embodiment for closing the end of a bore;

FIG. 90-91 are an illustration of another unitary crank-arm and spindlemember for the crank assembly of FIG. 52; and,

FIG. 92-99 are an illustration of a second portion crank arm for thecrank arm assembly of FIG. 52.

The detailed description explains embodiments of the invention, togetherwith advantages and features, by way of example with reference to thedrawings.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is an exemplary embodiment of a bicycle 100 having a bicycleframe 105 configured to receive front 110 and rear 115 wheels. Eachwheel includes an inflatable tire 112, 114 which is supported by a rim116, 118, respectively. The frame 105 includes a front section 120 and arear section 125. The front section 120 includes a head tube 130 that isconfigured and dimensioned to receive a front assembly 135 and to allowa rotational degree of freedom between the head tube 130 and a steerertube 140 in the front assembly 135. The front assembly 135 couples thefront section 120 to the front wheel 110. As will be discussed in moredetail below, the front assembly 135 may be provided in severaldifferent embodiments, including but not limited to: a unitary steerertube-crown-2-blade rigid fork arrangement; a unitary steerertube-crown-single rigid fork arrangement; a unitary steer tube-crownarrangement; a unitary steerer tube-crown-2-blade suspension forkarrangement; and a unitary steerer tube-crown-1-blade suspension forkarrangement.

A handle bar 145 is coupled to the steerer tube 140 to allow the riderto rotate the front wheel 110 via the front assembly 135. The handle bar145 typically has grips and hand brake actuators (not shown). On theopposite end of the frame front section 120, a vertically oriented rearseat support 160 is fixedly attached to at least one of the frontsection 120 and the rear section 125 provides support for seat 165. Acrank assembly 170 is mounted to the front section 120 below the seat165. As will be discussed in more detail below, the crank assembly 170includes a first portion having a first arm and an integral spindleextending therefrom. A second arm is coupled to the spindle opposite thefirst arm. Coupled to the ends of the crank arms are pedals (not shown).A rear wheel gear assembly (not shown) is coupled to the crank assembly170 via a chain or other suitable member.

The rear section 125 is coupled to the front section 120 by a pair oflinkages 172, 174 and a rear suspension system 175. The rear section 125includes an upper tube 180 and a lower tube 185 that connect the rearwheel 115 to the front section 120. It should be appreciated that thelinkages 172, 174 and rear suspension 175 pivot, allowing the rearsection 125 to move independently in the same plane as the front section120. This type of bicycle, sometimes referred to as a full suspensiontype, provides energy absorption and damping for both wheels 110, 115 ofthe bicycle 100. In an alternative embodiment, the rear suspension 175may be omitted, creating a bicycle type sometimes referred to as a hardtail, and the rear section 125 would be fixedly attached to the frontsection 120.

Referring now to FIG. 2, the front assembly 135 will be described. Thefront assembly 135 includes a steerer tube 140 that is coupled to rotatewithin the head tube 130. A crown 190 extends from the bottom of thesteerer tube 140 to provide an interface with a fork portion 192.Opposite the crown 190, dropouts 194 are coupled to the fork portion192. The dropouts 194 include a slot that is sized to receive an axle119 of front wheel 110. As will be discussed further below, the forkportion 192 may be coupled on both sides of the front wheel 110. In thisembodiment, a single suspension system may be incorporated, or each sideof the fork portion 192 may have a separate suspension system. The forkportion 192 with suspension may also be arranged on only one side of thebicycle (still referred to as a “fork” even though one “leg” or “blade”is absent), such as the left side for example, which is sometimesreferred to as a “lefty.”

During operation, the front assembly 135 absorbs a large amount ofenergy due to impacts on the front wheel 110. As such, it is desirablefor the front assembly 135 to be both strong enough to withstand theimpacts, ductile enough to avoid damage from the impacts and also belight in weight. An embodiment of a unitary and monolithic steerertube-crown 195 is illustrated in FIGS. 3-6. As used herein, the terms“unitary” and “monolithic” refer to the use of a single integral,seamless and contiguous material to form multiple functional parts of acomponent. In the exemplary embodiment, the components of the frontassembly 135 are formed from an aluminum material such as but notlimited to 6061-T6, 7075-T6, 7050-T73, 2024, 2014 or 6069 aluminumalloys.

In the embodiment shown in FIG. 3, the unitary steerer tube-crown 195includes a steerer tube 140 having an axial bore 196. A crown 190extends from one end of the steerer tube 140 with a first projection 198and a second projection 200. The projections 198, 200 each include anarm portion 206, 208 that extends on an angle away from the steerer tube140 and terminate in a flange 210, 212. An opening 202, 204 is formed ineach flange 210, 212 that is sized to receive a suspension fork. Theprojections 198, 200 extend on an angle relative to the axis of thesteerer tube 140.

The unitary steerer tube-crown 195 is formed from a metal, such asaluminum including but not limited to 6061-T6, 7075-T6, 7050-T73, 2024,2014 or 6069 aluminum alloys for example, by three-dimensional (3D)forging. Aluminum provides advantages over composite type materials inthat it is a high strength and ductile material and is also relativelylightweight. As will be discussed in more detail below, 3D forgingallows the forming of metallic articles such that, the article ishollow, while the interior and the exterior walls may be bent in any ofthe three dimensional directions.

The unitary steerer tube-crown 135 may have projections 198, 200 thatare solid such as is illustrated in FIG. 4. As discussed above, it isdesirable to lower the weight of components on the bicycle 100. Anotherembodiment of the unitary tube-crown 135 is shown in FIG. 5. In thisembodiment, bores 214, 216 are formed in the arms 206, 208 between theopenings 202, 204 and the axial bore 196. It should be appreciated thatthe bores 214, 216 reduce the weight of the unitary steerer tube-crown135. In the embodiment of FIG. 5, the bores 214, 216 are formed afterthe forging of the unitary steerer tube-crown 135 via the openings 202,204 by a machining operation.

Another embodiment of the unitary steerer tube-crown 135 is shown inFIG. 6. In this embodiment, a third bore 218 is formed between an end219 of the flange 210 and the opening 202. Similarly, a fourth bore 220is formed between an end 222 of flange 212 and the opening 204. In oneembodiment, the third bore 218 and the fourth bore 220 are coaxial withthe bore 214 and bore 216 respectively. In another embodiment, the bores218, 214 are formed in the same machining operation and the bore 220,216 are formed in the same machining operation.

Another embodiment of a unitary and monolithic steerer tube-crown-blade222 is illustrated in FIGS. 7-10. Similar to the unitary steerertube-crown 135, the unitary steerer tube-crown-blade 222 includes asteerer tube 140 having an axial bore 196. A crown 190 having a firstprojection 198 and a second projection 200 extend from the steerer tube140. A first blade 224 and a second blade 226 extend from theprojections 198, 200 respectively in the direction away from the steerertube 140. In one embodiment, the axis of the blades 224, 226 issubstantially parallel to the axis of the steerer tube 140. The blades224, 226 each include an axial bore 228, 230 that is open on an endopposite the crown 190. In one embodiment, a bore 232 is formed throughthe outside of the blade 224 and a bore 234 is formed through theoutside of blade 226. It should be appreciated that the bores 232, 234may extend through the first projection 198 and second projection 200into the axial bore 196, similar to the embodiment illustrated in FIG.6. Similar to above, the unitary steerer tube-crown-blade 222 is formedfrom a metal, such as aluminum including 6061-T6, 7075-T6, 7050-T73,2024, 2014 or 6069 aluminum alloys for example, by three-dimensional(3D) forging.

Similar to the embodiments illustrated in FIGS. 2-10, a unitary andmonolithic steerer tube-crown-fork 262 providing for a single forkportion 192 may be formed by 3D forging as shown in FIGS. 11-28. In theembodiment shown in FIGS. 11-16, steerer tube-crown-fork 262 includes asteerer tube 140 with a crown 264 extending from one end. The crown 264has a single projection 266 with a single flange 268 on an end oppositethe steerer tube 140. The flange 268 includes an opening 270 that issized to receive a suspension fork (not shown). In this embodiment, theflange 268 also has surface 272 that is on an angle 274 relative to atop surface 276. The angled surface 272 provides a relief that allows abore 278 to be formed in the projection 266. As discussed above, thebore 278 assists in reducing the weight of the steerer tube-crown-fork262.

The embodiment shown in FIGS. 17-22 illustrates a unitary steerertube-crown-fork 262 having a steerer tube 140, a crown 264 with aprojection 266. In this embodiment, a flange 278 is arranged on one endof the projection 266. The flange 278, includes a lower surface 280 andan upper surface 282 that are substantially parallel, and generallyperpendicular to the axis' 284, 288 of the bore 196 and opening 270respectively. The flange 278 is configured to extend a short distancefrom the lower surface 288 of the steerer tube 140. This arrangementprovides a larger surface area in the opening 270 of flange 278. Alarger surface area may be desirable to strengthen the connectionbetween the unitary steerer tube-crown-fork 262 and a suspension fork(not shown) for example. Since the lower surface 280 extends further, abore 290 may be formed through the outside diameter of the flange 278. Asecond bore 292 is also formed in the projection 266 to further reduceweight. It should be appreciated that the bores 290, 292 may be formedin the same operation and have the same general shape, or may havedifferent sizes and/or shapes.

The embodiment shown in FIGS. 23-28 illustrates a unitary steerertube-crown-fork 262 having a steerer tube 140, a crown 264 with aprojection 266. In this embodiment, a blade 294 extends from the end ofthe projection 266 in a direction substantially away from the steerertube 140. The blade 264 includes an opening 296 that extendstherethrough. The blade 264 forms part of the suspension fork (notshown) that connects the unitary steerer tube-crown-fork 262 to thewheel 110. It should be appreciated that the blade 264 may also betapered to form a rigid fork as discussed in more detail below. Similarto the embodiment above, a first bore 290 may be formed in the outerdiameter of the blade 264 and a second bore 292 may be formed in theprojection 266 as discussed above.

In some embodiments, the steerer tube 140 includes a bore 196. The bore196 may be a through bore, such as shown in the embodiments of FIG. 13and FIG. 19 for example. The bore 196 may have a closed end, sometimesreferred to as a blind hole, as shown in the embodiments of FIGS. 4-6and FIG. 25 for example. Similarly, the blade 224, 226, 294 and flange210, 212, 268 may have a through opening 202, 204, 270, 296 asillustrated in FIGS. 3-6 and FIGS. 11-28. The opening 202, 204, 270, 296may also have a closed end as shown in FIG. 30.

With reference to FIG. 29 and FIG. 30, the different embodiments for endconfigurations of the steerer tube 140, blade 224, 226, 294 and flange210, 212, 268 will be discussed. As mentioned above, the bore 196 mayhave a closed end 298 adjacent the crown 190, 264. In the exemplaryembodiment, the closed end 298 may be formed during the 3D forgingprocess. The closed end 298 may also be formed by secondary operations,such as by forming a through bore initially and secondarily welding amember over the end for example. By leaving the end 298 of the bore 196closed, advantages may be gained in providing a stronger and stifferstructure. It should be appreciated that in some embodiments, an openend of bore 196 may be desired to provide a lower weight.

Similar to bore 196, the opening 202, 204, 270, 296 may also have aclosed end 300. In the exemplary embodiment, the closed end 300 isformed during the 3D forging process of the blade or flange. The closedend 300 may also be formed by secondary operations, such as by forming athrough bore initially and secondarily welding a member over the end forexample. Similar to closed end 298, by having closed end 300, advantagesmay be gained in providing a stronger and stiffer structure. It shouldbe appreciated that in some embodiments, an open end of opening 202,204, 270, 296 may be desired to provide a lower weight or for theinstallation of spring and damping components for suspension.

It should also be appreciated that the steerer tube 140, blade 224, 226,294 and flange 210, 212, 268 may be arranged with any combination ofopen ends and closed ends 298, 300 depending on the desired performancefor the end application without deviating from the intended scope of theclaimed invention. Similarly, the projections 198, 200, 266 may includea bore, or may be solid depending on the desired performance for the endapplication without deviating from the intended scope of the claimedinvention.

It should further be appreciated that while the embodiments hereindescribe portions of the unitary steerer tube-crown 135, steerertube-crown-blade 222, and steerer tube-crown-fork 262 as being generallycylindrical, such as the blades 224, 226 and the steerer tube 140 forexample. This is for exemplary purposes and other shapes may also besuitable or desirable without deviating from the intended scope of theclaimed invention.

Turning now to FIGS. 31-38, a method of forming a unitary steerertube-crown-fork 236 using a multistage three-dimensional (“3D”) forgingis described. The unitary steerer tube-crown-fork 236 is similar to thesteerer tube-crown-blade 222 except the suspension fork is replaced witha rigid leg. The unitary steerer tube-crown-fork 236 forms a rigidconnection between the wheel 110 and the handlebar 145. It should beappreciated that the multistage 3D forging method of forming the unitarysteerer tube-crown-fork 236 may also be used to form the unitary steerertube-crown 135 and steerer tube-crown-blade 222.

The method starts with a billet 238, formed from a metal such asaluminum including 6061-T6, 7075-T6, 7050-T73, 2024, 2014 or 6069aluminum alloys for example, as illustrated in FIG. 31. The billet isthen forged to form a first projection 240 and a second projection 242as illustrated in FIG. 32. Next, the forged billet 238 is processedusing a 3D forging process to extend the second projection 242 to forman elongated second projection 246 (FIG. 33). During this first 3Dforging, a bore 244 is formed in the elongated projection 246.Similarly, using a second 3D forging process, the first projection 240is extended to form an elongated projection 248 and a bore 250 (FIG.34). As will be made clearer below, the elongated projections 246, 248form the fork legs (or the blades 224, 226 in the embodiment of theunitary steerer tube-crown-blade 222).

With the two elongated projections 246, 248 formed, the billet isprocessed using a third 3D forging step to form an elongated thirdprojection 252 with a bore 254 (FIG. 35). The third projection 252extends from the end of the billet 238 in a direction substantiallyperpendicular to the elongated projections 246, 248. The thirdprojection 252 is of a size and length to form a steerer tube 140. Next,the method performs a swaging operation on a portion 254, 256 of thefirst projection 248 and the second projection 246 respectively, that isdistal from the third projection 252 (FIG. 36). Swaging is a coldworking process using dies to produce a taper on the portions 254, 256,such that the end diameter of the elongated projections 246, 248 issmaller than the diameter adjacent to the third projection 252. Itshould be appreciated that in embodiments where the elongated portions246, 248 will form blades in a suspension fork, swaging operation may beeliminated. It is contemplated that 3D forging operations shown in FIGS.32-35 may be combined so the part shown in FIG. 35 is produced in asingle 3D forging operation from the billet shown in FIG. 31.

In some embodiments, additional operations may be performed on the firstprojection 248 and second projection 246 as is known in the art toobtain the desired blade shape. For example, the projections 246, 248may be “butted” to form a variable wall. The projections 246, 248 mayalso be formed to have non-round, a non-uniform, or variable shape alongtheir length for example.

Once the elongated projections 246, 248 are swaged, a bending operationis used to form a crown 190 and blades/fork-legs 258, 260 (FIG. 37).Finally, secondary operations are performed, such as machining the thirdprojection 252 to form the final dimensions of a steerer tube 140 or thewelding, brazing, bonding or joining of drop outs 194 (FIG. 38). Othersecondary operations may also include the forming of other features,such as bores 232, 234 for example.

Turning now to FIGS. 39-50, another exemplary method of forming aunitary steerer tube-crown-fork 402 using a multistage 3D forging isdescribed. The unitary steerer tube-crown-fork 402 is similar to thesteerer tube-crown-blade 236 except with a single rigid leg or blade.The unitary steerer tube-crown-fork 402 forms a rigid connection betweenthe wheel 110 and the handlebar 145.

The method starts with a billet 404, formed from a metal such asaluminum including 6061-T6, 7075-T6, 7050-T73, 2024, 2014 or 6069aluminum alloys for example, as illustrated in FIG. 39. The billet isthen bent to form the basic shape 406 of the unitary steerertube-crown-fork 402. The basic shape 406 includes a first portion 408that will form the steerer tube, a first projection 410 that will formthe leg or blade, and a second projection 412 that will be used to forma spindle. With the basic shape 406 formed, the next step involves atwo-dimensional forging process that forms the shape 414 as shown inFIG. 41. The forging mandrill in inserted in the direction indicated bythe arrow 416. This two-dimensional forging results in an elongatedsecond projection 412 having a smaller diameter.

With second projection 412 elongated, the billet 404 is subjected to a3D forging process that forms to spindle 418, brake tabs 420 and crown422 as shown in FIG. 42. The mandrill direction is indicated by thearrow 416. The 3D forging further forms the bore 424 (FIG. 45). Next,the method performs a second 3D forging process that shapes and extrudesfork blade 426 to desired length as shown in FIG. 43. The final shape428 is formed in a third 3D forging process that forms the top portion408 as shown in FIG. 44 into the steerer tube 430 and the bore 432 (FIG.45). It is contemplated that 3D forging operations shown in FIGS. 41-44may be combined so the final shape 428 is produced in a single 3Dforging operation following the two-dimensional forging process.

In some embodiments, it is desirable to close the end of bore 424 usinga blade insert 434 as shown in FIGS. 46-48. In the exemplary embodiment,the blade insert 434 is arranged and bonded within bore 424. The bladeinsert 434 closes the end of the bore 424 and stabilizes the end of thespindle 418. Finally, secondary operations may be performed, such asmachining the steerer tube 430 to final dimensions to form the finalunitary steerer-tube-crown-fork 402 shown in FIGS. 49-50.

It should be appreciated that the 3D forging process discussed inreference to FIGS. 42-44 may also be used to fabricate a unitary steerertube-crown-blade configuration shown in FIG. 51. This embodiment issubstantially similar to the unitary steerer tube-crown-blade 222illustrated in FIGS. 7-10. In this embodiment, a 3D forging step isincluded to form the wheel mounting interface or dropouts 194 and thebrake mounts 420 on substantially opposite sides of the forks or blades224, 226.

The 3D forging process described above may also be used with othercomponents of bicycle 100 to gain the advantage of reducing the numberof parts while reducing weight and maintaining a high strength andductile material performance. Turning now to FIGS. 52-99 a low weight,reduced part count, high strength crank assembly 170 and a method offabrication will be described.

The crank assembly 170 includes a first portion 302, a second portion304, a spider 306, a lock ring 308, and a bolt 309 as shown in FIG. 52.The first portion 302 includes an unitary and monolithic arm-spindlemember 310 that is formed from a metallic material, such as aluminumincluding but not limited to 6061-T6, 7075-T6, 7050-T73, 2024, 2014 or6069 aluminum alloys for example. The first portion 302 is formed by a3D forging process will be described in more detail below. The unitarymember 310 includes an arm portion 312 with the spindle portion 314extending from one end. The unitary member 310 also includes featuressuch as a spider interface 316 and a second portion interface 318. Firstportion 302 may also include a pedal (not shown) that couples to theunitary member 310 by an opening 320 in the arm 312. In anotherembodiment, the spider 306 may be formed through a 3D forging operationas a unitary part of the unitary member 310. This would eliminate themachining of the spider interface 316 and the lock ring 308 as well. Amodular separable spider 306 may, however, provide advantages byallowing the use of the crank assembly 170 on a variety of bicyclemodels (e.g. road bikes, mountain bikes etc.).

The second portion 304 includes an arm portion 322 that is similar insize and shape to the arm 312. A boss 324 extends from one end of thearm 322. The boss 324 includes an opening 326 with features that aresized and shaped to receive the second portion interface 318 and thespindle 314. A fastener 309 extends through the opening 326 and thespindle 314 to couple the first portion 302 to the second portion 304when the crank assembly 170 is mounted to the bicycle 100.

A process for forming the first portion 302 is shown in FIGS. 52-59. Theprocess begins with a billet 328 made from a metallic material, such asaluminum including but not limited to 6061-T6, 7075-T6, 7050-T73, 2024,2014 or 6069 aluminum alloys for example (FIG. 53). The billet undergoesa first forging process in FIG. 54 to form a generally rectangularportion 330. The first forging process may also form a step 331 in thebillet 328 forming a smaller diameter portion 333 as shown in FIG. 61.The smaller diameter portion 333 may further include a small taperedsection 335. In some embodiments, the step 331 provides a surfaceagainst which the spider 306 is positioned. The tapered section may alsoform the second portion interface 318 during secondary operations.

The billet 328 is then processed with a first 3D forging operation toform the arm 312 with an axial bore 332 and a solid portion 334 on oneend as shown in FIGS. 55-56 and FIGS. 61-65. The arm 312 is formed on anangle 350 (FIG. 67) relative to the axis 352 of the spindle 314. In oneembodiment, the arm 312 has a curved first wall 336 and curved secondwall 338. The curved walls 336, 338 are connected by a third wall 340and a fourth wall 342 as shown in FIG. 65. The walls 336, 338, 340, 342define the axial bore 332. In one embodiment, illustrated in FIG. 66,the curved walls 336, 338 have a first thickness 344 and the connectingwalls 340, 342 have a second thickness 346. In the exemplary embodiment,the first thickness 344 is one-half the width of the second thickness342. In one embodiment, the first thickness 344 is 2 millimeters and thesecond thickness 342 is 4 millimeters.

With the arm 312 formed, the process then extends the smaller diameterportion 331 with a second 3D forging to form a spindle 314 as shown inFIGS. 57-58 and FIGS. 67-71. The spindle 314 is formed with an axialbore 348. The axial bore 348 intersects the axial bore 332 of the arm312. In one embodiment, the axial bore 348 is formed during the second3D forging step as a blind hole to extend through the arm 312 as shownin FIGS. 67-71. In another embodiment, the bore 348 is formed as a blindhole with an opening on the end 354 of the spindle 314, as shown inFIGS. 57-58. In either embodiment, the bore 348 is subsequently extendedto be a through-hole during secondary operations. In the exemplaryembodiment, the spindle 314 has a 30 millimeter outer diameter

After forming the spindle 314, the process then performs a bendingoperation on the arm 312 as shown in FIG. 59 and FIGS. 72-76. In oneembodiment, the bending operation changes the angle of a portion 356 ofarm 312 from being oriented on an angle 350 to being substantiallyperpendicular to the axis 352. A second portion 358 remains oriented onthe angle 350.

The next step in the process is to close the end of the axial bore 332.It should be appreciated that the arm 312 and spindle 314 transfer thebicycle rider's energy during each stroke resulting in a large loadbeing applied to the area of the first portion 302 where the arm 312 andspindle 314 intersect. To strengthen and stiffen this intersection, apin or plug 360 is inserted into the axial bore 332 (FIGS. 77-87). Theplug 360 is shaped to conform to the shape of the axial bore 332, suchas an arcuate surface 362 to match the curved walls 336, 338 forexample. Plug 360 may also includes a hole 364 sized to substantiallythe same size and shape as the axial bore 348. When inserted in theaxial bore 232, plug 360 is arranged such that the hole 62 is coaxialwith the axial bore 348. The plug 360 is coupled to the first portion302 such as by a press fit, bonding or brazing for example.

In another embodiment, the end of the axial bore 332 is closed in aforging process instead of with plug 360, as is shown in FIGS. 88-89. Inthis embodiment, a projection 368 is formed on the wall 336 opposite thespindle 314. The projection 368 may be formed during one of the 3Dforging processes, such as that shown in FIG. 57-58 for example. Toclose the end of the axial bore 332, the projection 368 is processed ina forging that displaces the material of the projection 368 into theopening 370 in the axial bore 332. This closes the opening 370 andresults in a substantially smooth outer surface on wall 336 as shown inFIG. 89.

With the plug 360 secured, or the axial bore 332 otherwise closed, theprocess finishes the unitary member 310 with secondary machiningoperations to the spindle 314 to form the spider interface 316, thesecond portion interface 318 and the extension 366 of the axial bore 348into a through-hole as shown in FIG. 60 and FIGS. 81-87. The opening 320is formed in the solid portion 334 for mounting the pedals.

In another embodiment, a similar process to that described above may beused to perform the 3D forgings from the pedal end of the arm as shownin FIGS. 90-91 In the embodiment shown in FIG. 90, the arm 312 is formedin a 3D forging with the opening 370 positioned on the opposite end ofthe arm 312 from the spindle 314. A projection 372 is formed on the arm312 adjacent the opening 370 to allow a forging step to close theopening 370 and form the solid portion 334. Once the solid portion 334is formed, the spindle 314 is formed by a 3D forging as described above.

In the embodiment shown in FIG. 91, the arm 312 is formed in a 3Dforging with the opening 370 positioned on the opposite end of the arm312 from the spindle 314. A projection 372 is formed on the arm 312adjacent the opening 370 the spindle 314 is formed by a 3D forging witha projection 374 on an end of the spindle 314 opposite the arm 312. Theprojection 374 is then displaced in a forging operation to close the end354 of the axial bore 348. Finally, a forging step displaces material toclose the opening 370 and form the solid portion 334.

The second portion 304 shown in FIGS. 92-99 may also be formed from aseries of 3D forging processes substantially similar to that describedwith regards to the first portion 302. A billet is forged to form arectangular portion similar to rectangular portion 334. The arm 322having an axial bore 376 is then formed with a 3D forging with the axialbore 376 being formed from a pair of opposing curved walls 378, 380. Apair of connecting walls 382, 384 connects the curved walls 378, 380. Inone embodiment curved walls 378, 380 have a thickness 386 that isone-half the thickness 388 of the connecting walls 382, 384. In oneembodiment, the thickness 386 is 2 millimeters and thickness 388 is 4millimeters.

As with the spindle 314 of first portion 302, the boss 324 is thenextended in a 3D forging operation. The opening 326 is formed partiallyin the 3D forging step, with the opening 326 being extended into athrough-hole with a secondary operation. With the boss 324 formed, thearm 322 is bent with a first portion 390 being substantiallyperpendicular to an axis 392 of opening 326. A second portion 394remains on an angle 396 (FIG. 98) relative to the axis 392. Once the arm322 is bent, secondary machining operations are performed to form theopening 398 for the pedal (not shown) and the features 400 in opening326 that couple to the second portion interface 318.

An embodiment of the invention, as shown and described by the variousfigures and accompanying text, provides a bicycle having one or more ofthe following features: a unitary and monolithic steerer tube and crown;a unitary and monolithic steerer tube, crown and front blades; a unitarymonolithic crank arm and spindle; a hollow crank arm formed by 3Dforging; and a monolithic and unitary fork assembly having a steerertube, crown and blades formed by 3D forging. These features may have oneor more of the following advantages over the prior art: lower in weight,higher strength, greater ductility, lower manufacturing cost, fasterassembly and lower number of parts and components.

In accordance with one embodiment of the invention, a bicycle a bicycleis provided having a wheel, a head tube, and, a unitary fork operablycoupled to said wheel. The fork includes a steerer tube operably coupledto the head tube, where the steerer tube includes a first bore having afirst axis. A crown extends contiguously from one end of the steerertube, wherein the fork is made from a three-dimensional (3D) forgedmetal material. In one embodiment, the crown comprises a firstprojection having a first opening, the first opening having a secondaxis, wherein the second axis is substantially parallel with the firstaxis. The crown may further comprise a second projection with a secondopening, the second opening having a third axis, wherein the third axisis substantially parallel with the first axis. In another embodiment,the crown further comprises a second bore extending between the firstopening and the first bore. In yet another embodiment, the crown furthercomprises a third bore extending from the first opening through an endof the first projection, wherein the third bore is coaxial with thefirst bore. In yet another embodiment, the first bore is closed on anend adjacent the crown. In yet another embodiment, the first opening isclosed on an end adjacent the crown. In yet another embodiment, the forkfurther comprises a first projection extending contiguously from crown,and a first blade extends contiguously from the first projection in adirection substantially opposite the steerer tube. In yet anotherembodiment, the fork further comprises a second projection extendingcontiguously from the crown, and a second blade extends contiguouslyfrom the second projection, wherein the second blade is substantiallyparallel to the first blade. In yet another embodiment, the bicyclefurther includes a first dropout coupled to an end of the first bladeopposite the crown and a second dropout is coupled to an end of thesecond blade opposite the crown.

In accordance with another embodiment, a method of fabricating a unitarybicycle fork is provided. The method includes performing a first forgingon a billet to form a first projection. A first 3D forging is performedon the billet extending the first projection to form a crown. A second3D forging is performed on the billet to form a steering tube, whereinthe second projection is substantially perpendicular to the firstprojection. A first end of the first projection is swaged to form ablade. The first projection is bent in a direction opposite the secondprojection. A first drop out is joined on the first projection. A thirdprojection is formed when performing the first forging on the billet. Athird 3D forging is performed on the billet extending the thirdprojection after the step of extending the first projection. The firstprojection is bent a direction opposite the second projection. The thirdprojection is bent in a direction opposite the second projection afterbending the first projection. A first drop out is joined to the firstprojection and a second drop out is joined to second projection. A firstend of the first projection is swaged to form a blade and a second endof the third projection is also swaged. An opening is formed in thefirst projection, wherein the opening is substantially parallel to thesecond projection. A first bore is formed between the first opening anda second bore in the second projection. A third bore is formed betweenthe first opening and an end of the first projection, wherein the thirdbore is substantially coaxial with the first bore. In one embodiment,the first projection includes a first axial bore having a closed endadjacent the second projection and the second projection includes asecond axial bore having a closed end adjacent the first projection.

In accordance with another embodiment, a unitary bicycle fork isprovided having a crown formed by a first 3D forging of a metal billetto form a first projection. A steerer tube is extended from the crown,the steerer tube formed by a second 3D forging, the steerer tube havinga first axial bore therein. The crown further includes a first opening,the first opening being substantially parallel to the first axial bore.A second bore is arranged between the first bore and the first opening.A third bore is arranged between the first opening and an end of thecrown, wherein the third bore is substantially coaxial with said secondbore. A first blade extends from the crown, the first blade being formedfrom a first portion of the first projection wherein the first portionis swaged and then bent to extend in a direction opposite from thesteerer tube and the first opening extends axially within the firstblade. The first opening may also includes a closed end adjacent thesteerer tube. The first bore may also include a closed end adjacent thecrown. A second blade is extended from the crown, wherein the crown isformed by the first projection and a second projection during the first3D forging, the second blade being formed from a second portion of thesecond projection, wherein the second portion is swaged and then bent toextend in a direction opposite the steerer tube. A first dropout iscoupled to an end of the first blade opposite the crown, and a seconddropout is coupled to an end of the second blade opposite the crown.

In accordance with another embodiment, a crank assembly for a bicycle isprovided having a unitary first portion. The first portion includes afirst arm having a first solid end and an first axial bore extendingfrom the first end to a second end. The first portion also includes aspindle extending substantially perpendicular from the arm adjacent thesecond end, the spindle having a second axial bore extending into thefirst arm adjacent the second end, the second axial bore being arrangedto intersection with the first axial bore. A second portion is providedhaving a second arm having a third solid end and an third axial boreextending from the third end to a fourth end, the second portion beingoperably coupled to the spindle adjacent the fourth end. The first armmay include a curved first wall and a curved second wall opposite thefirst wall, wherein the spindle extends from the second wall. A thirdwall is arranged between the first wall and the second wall and a fourthwall is arranged between the first wall and the second wall opposite thethird wall. Wherein the first wall the second wall, the third wall andthe fourth wall define the first axial bore. In one embodiment, thefirst wall and the second wall have a first thickness and the third walland the fourth wall have a second thickness. In another embodiment, thefirst thickness is substantially one-half said second thickness. Inanother embodiment, the first thickness is 2 millimeters and the secondthickness is 4 millimeters. The crank assembly may also include a plugcoupled to the first arm in the first axial bore adjacent the secondend. In one embodiment, the crank assembly may also include a firstprojection extending from the first wall adjacent the second end,wherein the first projection is forged to close said first axial bore atthe second end.

In accordance with another embodiment, a method of fabricating a unitarybicycle crank-arm and spindle is provided. The method includes forming afirst elongated arm by 3D forging, the first arm having a solid firstend and a first axial bore, the axial bore having a first opening at asecond end of the first arm opposite the first end. A first projectionis formed on the first arm adjacent the second end. A spindle is formedby extending the first projection and forming a second axial bore in thefirst projection by 3D forging. The first arm is bent such that thesolid end is substantially perpendicular to the first projection. Asecond elongated arm is formed by 3D forging, the second arm having asold third end and a third axial bore, the third axial bore having asecond opening at a fourth end of the second arm. A second projection isformed on the second elongated arm adjacent the third end. A fourthaxial bore is formed in the second projection, wherein the fourth axialbore is sized to receive the spindle opposite the first arm. A firstplug is inserted into the first opening and a second plug is insertedinto the second opening. The first plug and second plug are coupled tothe first arm and second arm by a pressfit, brazing or bonding.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims. Also, in the drawings and thedescription, there have been disclosed exemplary embodiments of theinvention and, although specific terms may have been employed, they areunless otherwise stated used in a generic and descriptive sense only andnot for purposes of limitation, the scope of the invention therefore notbeing so limited. Moreover, the use of the terms first, second, front,rear, top, bottom, upper, lower etc. do not denote any orientation,order or importance, but rather the terms first, second, etc. are usedto distinguish one element from another. Furthermore, the use of theterms a, an, etc. do not denote a limitation of quantity, but ratherdenote the presence of at least one of the referenced item.

The invention claimed is:
 1. A method of fabricating an integrallyformed unitary bicycle crank-arm spindle comprising: forming a firstelongated arm by three-dimensional (3D) forging, said first elongatedarm having a solid pedal end portion and a first axial bore, said firstaxial bore having a first opening extending through a second end of saidfirst elongated arm opposite said solid pedal end portion, said firstaxial bore having a closed end opposite the first opening, the closedend being adjacent the solid pedal end portion; forming a firstprojection on said first elongated arm adjacent said second end andopposite said solid pedal end portion; forming an elongated spindle fromsaid first elongated arm by extending said first projection and forminga second axial bore in said first projection by 3D forging, theelongated spindle having an end opposite the first arm configured tocouple to a second elongated arm, the second axial bore defining an axisof rotation of the first elongated arm when installed on a bicycle, saidspindle being unitary and monolithic with said first elongated arm,wherein said second axial bore intersects and is contiguous with saidfirst axial bore; bending said first elongated arm, wherein said solidpedal end portion is substantially perpendicular to said firstprojection; forming the second elongated arm by 3D forging, said secondelongated arm having a third end and a third axial bore, said thirdaxial bore having a second opening at a fourth end of said secondelongated arm; forming a second projection on said second elongated armadjacent said third end; and, forming a fourth axial bore in said secondprojection, wherein said fourth axial bore is sized to receive saidspindle opposite said first elongated arm; and inserting the spindle inthe fourth axial bore to form a crank-arm spindle assembly.
 2. Themethod of claim 1 further comprising: inserting a first plug into saidfirst opening, said first plug having third opening, said third openingbeing substantially co-axial with said second axial bore when the firstplug is inserted into said first opening; and, inserting a second pluginto said second opening, said second plug having a fourth opening, saidfourth opening being substantially co-axial with said second axial borewhen said second plug is inserted into said second opening.
 3. Themethod of claim 2 further comprising: coupling said first plug to saidfirst elongated arm by brazing; and, coupling said second plug to saidsecond elongated arm by brazing.
 4. The method of claim 2 furthercomprising: coupling said first plug to said first elongated arm bybonding; and, coupling said second plug to said second elongated arm bybonding.